The present invention relates to an optical guide fixture for coupling visual information on a surface to an optical viewer. More particularly, the invention provides an apparatus having such an optical guide fixture for convenient viewing of visual information present on a surface.
A number of devices are known for assisting an individual having a visual impairment to view visual information, such as text and graphics, on a surface. Some such devices employ a scanner, such as a mouse-like device, having an optical receiver therein to obtain data corresponding to the visual information on the surface, and to transmit the data to a closed circuit television (CCTV) to be viewed on a television monitor. For example, U.S. Pat. No. 5,046,163 describes such a device. Such conventional devices are typically bulky, and hence are not easily portable. Further, an individual employing such a device can not easily determine which portion of the surface is being shown on the monitor because the scanner partially obstructs the surface. In addition, the scanner of such a device is typically bulky and hence is not suitable for scanning areas of the surface that are not easily accessible, such as the border areas between two adjacent pages of a book.
Another conventional system includes a head-mounted display unit coupled to a camera for viewing visual information on a surface. Such a system typically does not provide a mechanism for conveniently aiming the camera at a selected portion of the surface. This can lead to confusion, especially for a visually impaired patient, regarding which portion of the surface is being viewed. In addition, a person other than the viewer can not easily determine which portion of the surface is being viewed. This is particularly disadvantageous in an educational setting, for example, where an instructor is helping a patient read a book. In addition, such systems are typically heavy, and are cumbersome to wear.
Another conventional system, described in U.S. Pat. No. 4,330,169, includes a scanning head coupled to a bundle of optical fibers. A visually impaired individual views a portion of a surface bearing visual information by looking through a telescope that is coupled to the optical fibers. The scanning head of this device has a relatively narrow field of view. Further, the field of view of the fibers and that of the scanning head are different. Further, the scanning head of this patent is rotationally symmetric, thereby rendering rotational alignment of the scanning head relative to the surface and/or guided translation of the scanning head along a selected direction over the surface difficult. Another defect of the system of the ""169 patent is that the telescope does not follow the movements of the patient""s head. Accordingly, the patient must keep the head stationary relative to the telescope in order not to lose the view of the surface. This can lead to fatigue and renders viewing of the surface over a long period inconvenient.
An optical scanning instrument designed to alleviate some of these concerns would be advantageous to many people with vision impairment.
The present invention provides an optical guide fixture that is adapted for coupling visual information on a surface to an optical receiver having a field of view. An optical guide fixture may comprise a pedestal coupled to an optical output window and/or a mount for an optical receiver having an output window. The term xe2x80x9cwindowxe2x80x9d as used herein refers to both an optical opening and to an optical aperture having an optically transparent material. The pedestal may have a base configured for manual translation across a surface, such that the output window and/or mount is maintained at a substantially constant distance and angle with respect to the surface. The field of view preferably does not include any opaque portions of the pedestal.
In certain embodiments, the field of view is visible external to the optical fixture. In one such embodiment, for example, the pedestal may be formed, at least in part, of an optically transmissive material, such as clear plastic or glass. In a further illustrative embodiment, the pedestal may provide an opening or aperture that permits external viewing of the field of view. In yet another embodiment, the pedestal includes a substantially skeletal structure, such as a tripod, that does not substantially obstruct the field of view, and/or the field of view may be substantially adjacent to the pedestal.
In certain embodiments, the optical fixture may be configured such that an implement, such as a stylus or pointer, external to the optical fixture may be introduced into or removed from the field of view. For example, the field of view may lie substantially external to the pedestal. Alternatively, the field of view may lie substantially internal to the pedestal, and the pedestal may comprise an aperture, such as an opening or gap, or the pedestal may comprise a substantially skeletal structure, such as a tripod. In such embodiments, the user can interact with the input window, e.g., with a writing implement, pointer, or other object, while the device is in use.
The pedestal of the optical fixture may be of any of various shapes. One common shape is tubular, and can be of constant cross-section or of varying cross-section, as in a cone or funnel shape. Further, the pedestal may have manually engageable guide elements that are mounted with the pedestal and are adapted for disposing the pedestal of the optical fixture on the surface with the field of view in selected placement and selected rotational alignment on the surface. The manually engageable guide elements can form a single, integral unit with the pedestal, or alternatively can be formed as a separate structure for attachment to the pedestal.
According to another aspect, the manually engageable guide elements of the optical fixture may include a handle region on the outer surface of the pedestal of the fixture. The handle region can include a manually perceptible surface irregularity, such as a flat portion, for positioning the fixture with a selected rotational alignment on a surface bearing visual information, and for manually guided translation of the optical fixture in a selected direction on the surface.
In certain embodiments, the optical axis of the optical output window and/or optical receiver is substantially collinear with the central axis of the pedestal. For example, the pedestal may have opposed ends, where each end forms an optical window. The two windows of the optical guide fixture may be in optical communication with each other, and be spaced apart by a predetermined distance along an optical axis. An input window of the optical fixture may be adapted for manually guided translation along the surface on which the visual information resides, and an output window of the fixture may be adapted for coupling with an optical receiver so that the receiver can receive optical information present at the input window. In certain such embodiments, the pedestal of the optical guide fixture may be hollow to provide an optical path along the optical axis for optical communication between the input and the output windows of the fixture. In another such embodiment, the pedestal of the fixture can be solid, and can be formed of an optically transparent material, such as clear plastic or glass.
According to another aspect of the invention wherein the optical axis of the optical output window and/or optical receiver is substantially collinear with the central axis of the pedestal, at least a portion of the pedestal of the optical guide fixture may have a cross-section, transverse to the optical axis of the fixture, that progressively increases in size along the optical axis so that the input window is larger than the output window. In one embodiment of the optical guide fixture, this cross-section is circular and the portion of the fixture having this circular cross-section has a conical shape. In one embodiment, the pedestal of the optical fixture may have a skeletal structure, such as a tripod.
In certain embodiments wherein the optical axis of the optical output window and/or optical receiver is substantially collinear with the central axis of the pedestal, the pedestal of the optical guide fixture, when the input window is placed on a surface, forms a closed space. In certain other related embodiments, the pedestal includes at least one aperture, gap, or space through which an implement may be inserted when the input window is placed on a surface. In other words, when the pedestal is placed on a surface, an object may be removably and replaceably passed from outside the fixture into the optical passage within the fixture.
In accordance with another aspect of the invention, the optical guide fixture may include an optical receiver, such as a digital camera, coupled to the output window of the fixture, i.e., the window opposite to the input window, which, in turn, is adapted for positioning on a surface bearing visual information. The optical receiver may have a predetermined focal length and be coupled to the optical fixture such that it is spaced from the input window, and thereby from the surface, by a distance substantially equal to the focal length.
The optical receiver provides an image of a portion of the surface that is within the field of view of the receiver. In embodiments wherein the optical axis of the optical output window and/or optical receiver is substantially collinear with the central axis of the pedestal, the optical receiver may be selected to have a field of view corresponding to the field of view of the input window of the fixture.
In certain embodiments wherein the optical axis of the optical output window and/or optical receiver is substantially collinear with the central axis of the pedestal, another aspect of the invention couples an optical receiver to the output window of the fixture, and further optionally disposes a lens within the pedestal of the optical fixture between the input and the output windows. The lens may be positioned within the pedestal such that the optical receiver and the input window, i.e., the window contacting the surface, lie substantially in conjugate planes of the lens. Thus, the lens focuses light emanating from at least a portion of the surface within the field of view of the first window onto the optical receiver, to provide an image of that portion of the surface which is within the field of view of the input optical window.
In another aspect, the invention provides a system for viewing visual information present on a surface. The system includes an optical guide fixture coupled to an optical receiver, such as a digital camera, as described above, and further includes a head-mounted display unit that is operably coupled to the optical receiver. The optical receiver receives visual information within the field of view of a window of the fixture contacting the surface, and transmits data corresponding to this visual information to the head-mounted display unit. One preferred head-mounted display unit includes liquid crystal display (LCD) elements that provide an image of the visual information to a viewer wearing the head-mounted display unit.
According to a further optional aspect of the invention, the head-mounted display unit includes a holder for removably and replaceably attaching the optical guide fixture thereto. This allows a viewer to view a surface, such as a page of a book, by bringing the surface into contact with a window of the optical fixture, and turning the head to scan different portions of the surface.
The system of the invention for viewing visual information can include a control unit that optionally allows altering the contrast polarity and/or the intensity contrast of the image that the head-mounted display unit presents to the viewer.
In another aspect of the invention, the head-mounted display unit includes only one viewing screen that can be placed in front of a selected eye of the viewer, and can be easily moved from one location to another within the display unit, for example, the screen can be moved from a first location corresponding to one eye of the viewer to a second location corresponding to the other eye of the viewer.
Another aspect of the invention optionally mounts at least one corrective lens to the head-mounted display unit to provide additional visual aid to the viewer.
According to another aspect of the invention, a filter, mounted to the head-mounted display unit, filters a selected range of electromagnetic wavelengths of the image presented to the viewer.
In another aspect, one or more prisms, mounted to the head-mounted display unit provide selective deflections of the light rays emanating from an image presented by the head-mounted display unit. Such selective deflections of the light rays can advantageously allow a patient having macular degeneration to view the image without a need to move her eye to focus the image on the functional portions of the retina.
These and other features of the invention are more fully set forth below with reference to the illustrated embodiments, and the accompanying drawings.